Hybrid vehicles configured such that a rotating electric machine generates a vehicle driving force using electric power from a secondary battery mounted in a vehicle have been attracting attention.
Japanese Patent Laying-Open No. 2008-285011 (PTL 1) describes a hybrid vehicle in which selection is made between a mode in which the vehicle travels by operating at least an engine and a mode in which the vehicle travels by stopping the engine and using only an output of a motor generator. PTL 1 describes that, in the hybrid vehicle, replacement timing of consumable parts related to the engine is determined based on an operation result of the engine.
Further, hybrid vehicles require traveling control which can avoid excessive charging/discharging of a vehicle-mounted secondary battery and also ensure driving performance in response to a driver's request. Japanese Patent Laying-Open No. 2006-109650 (PTL 2) describes a control device for a vehicle and a method for controlling a vehicle. PTL 2 describes that an upper limit value or a lower limit value of the amount of change of a torque generated by a traction motor serving as a rotating electric machine generating a vehicle driving force is set based on a limit value of output power or input power of a secondary battery and a speed of the vehicle. Thereby, it is aimed that the traction motor outputs a torque requested by a driver without causing excessive charging/discharging of the secondary battery.
As described in PTL 2, it is common to set upper limit values of input power and output power of a secondary battery based on a state of charge (SOC) and a temperature of the secondary battery. An output of a traction motor is set in a range where the output power of the secondary battery does not exceed the upper limit value. Thus, if the output power upper limit value is limited due to a reduction in the SOC or an increase in the temperature of the secondary battery, the output of the traction motor is also limited.